Apparatus for manufacturing expansion joints



July 21, 1964 J. P. ZALLEA 3,141,495

APPARATUS FOR MANUFACTURING EXPANSION JOINTS Original Filed May 20, 19584 Sheets-Sheet 1 INVENTOR. \mmss P. ZHLLEH ATTORNEY July 21, 1964 J. P.ZALLEA 3,141,495

APPARATUS FOR MANUFACTURING EXPANSION JOINTS Original Filed May 20 19584 Sheets-Sheet 2 INVENTOR.

amass P. 'ZHLLEA 63 J nTToRma APPARATUS FOR MANUFACTURING EXPANSIONJOINTS Original Filed May 20 1958 J. P. ZALLEA July 21, 1964 4Sheets-Sheet 3 INVENT OR.

JAMES P. ZA A BY Z 22 Z ATTORIUEV July 21, 1964 ZALLEA 3,141,495

APPARATUS FOR MANUFACTURING EXPANSION JOINTS Original Filed May 20, 19584 4 Sheets-Sheet 4 I I INVENTOR.

M55 P. ZFILLEH so) A? RTTOQIIIEY United States Patent 3,141,495APPARATUS FOR MANUFACTURING EXPANSION JQINTS James P. Zallea,Wilmington, Del., assignor, by mesne assignments, to Zallea Brothers,Inc., Wilmington, DeL, a corporation of Delaware Original applicationMay 20, 1958, Ser. No. 736,605, now Patent No. 3,091,025, dated May 28,1963. Divided and this application July 10, I961, Ser. No. 123,066

3 Claims. (Cl. 15340) This invention relates to apparatus for and themethod of fabricating hollow equalizing rings for use withselfequalizing expansion joints, this application being a division of myco-pending application serial No. 736,605, filed May 20, 1958, nowmatured as Patent No. 3,091,- 025, dated May 28, 1963.

A principal object of this invention is to provide a method offabricating equalizing rings that have a minimum of circumferentiallyextending welds.

Another object of this invention is to provide a method of fabricatingequalizing rings which comprise a pair of hollow one-piece semi-circularsections that conjointly form a hollow toroid.

Still another object of this invention is to facilitate the manufactureof the equalizing rings by a method which involves a minimum number offabricating operations, thereby enabling the rings to be formed from aminimum number of parts.

These and other objects and advantages of my invention will becomeapparent to those persons normally skilled in the art from a carefulreading of the following specification and the accompanying drawings,wherein:

FIGURE 1 illustrates the apparatus for bending channel or tear-dropcross-section stock into a hollow annulus;

FIGURES 2, 3, and 4 illustrate various stages of the annulus formingprocess;

FIGURE 5 illustrates a sectional View taken along the lines 55 of FIGURE1, some parts being shown in section and other parts in elevation;

FIGURE 6 is an alternative showing to that of FIG- URE 5 illustrating apart of the forming apparatus employed where the stock to be rolled isof tear-drop crosssection rather than open channel;

FIGURE 7 is a view taken along the lines 77 of FIG- URE 1 illustrating aforming block which is used to transform open channel stock to atear-drop cross-section just prior to the actual bending operation;

FIGURE 8 is a sectional view taken along the lines 88 of FIGURE 1illustrating open channel stock being transformed into the tear-dropcross-section by means of the forming block of FIGURE 7;

FIGURE 9 is a sectional view taken along the lines 9-9 of FIGURE 1illustrating the completion of the tear-drop forming operation from theopen channel stock;

FIGURE 10 is a sectional view taken along the lines 10-10 of FIGURE 2illustrating a typical clamping mechanism for securing the rolled stockto a ring forming die;

FIGURE 11 is a section view taken along the lines 11-11 of FIGURE 2;

FIGURE 12 is a plan View of apparatus for cutting to size a rolledannulus such as that illustrated in FIG- URE 4;

FIGURE 13 is a view taken along the lines 13-13 of FIGURE 12;

FIGURE 14 is a sectional view taken along the lines 14-14 of FIGURE 12;

FIGURE 15 is a plan view of apparatus for positioning the sized annuluson a welding jig;

FIGURE 16 illustrates the apparatus of FIGURE 14 3,141,495 Patented July21, 1964 Tee with the annulus clamped in place and the outer band inposition for welding thereto;

FIGURE 17 is a detailed view of the apparatus within the phantom circleof FIGURE 16;

FIGURE 18 is a view taken along the lines 1818 of FIGURE 17, some partsbeing shown in section and others in elevation;

FIGURE 19 illustrates a completed equalizing ring after demounting fromthe welding jig illustrated in FIG- URE 16;

FIGURE 20 illustrates the equalizing ring of FIG- URE 19 which has beensplit into two semi-circular sections and has had butt straps filletwelded to the outer band;

FIGURE 21 illustrates a cross-sectional view of a finished equalizingring showing a butt strap fillet welded to the outer band. Thissectional view is taken along the lines 2121 of FIGURE 20;

FIGURE 22 illustrates a split equalizing ring which has a pair ofbolting lugs welded to the outer band; and

FIGURE 23 is a sectional view illustrating an equalizing ring in placeabout a bellows expansion joint.

In the various views like elements are denoted by like referencecharacters.

Briefly, the method of making the equalizing rings includes threeessentially separate operations. The first of these operations is a rollforming procedure in which a pieceof straight stock is formed into anannulus, and details of this portion of the fabrication method areillustrated in the first 11 figures of the drawings. The second part ofthe fabrication method deals with the operations of sizing and trimmingthe annulus to prepare the latter for welding to an outer band which,with the annulus forms the T-shaped equalizing ring, the details ofwhich are illustrated in connection with FIGURES 12 through 14. Thethird part .of the fabrication deals with the welding of the outer bandto the rolled annulus and will be described in connection with FIGURES15 through 18. Turn now to an examination of the FIG- URES 1 through 11for an understanding of the process of roll forming straight stock intoan annulus.

FIGURE 1 illustrates the apparatus used in the roll forming process. Thebasic apparatus required for this roll forming operation is a slow speedpower driven table capable of rotation in a horizontal plane. A verticalboring mill or turret lathe with a table size large enough toaccommodate the annulus diameter desired has been found to operatesatisfactorily with table rotation speeds in the range of approximatelyone to three revolutions per minute. In FIGURE 1 this table isillustrated as the table 30. The table 30 is cross-slotted as at '31,and radially slidably fitted into these slots 31 are fouradjustablejawchucks 32. The chucks 32 clamp a circular die 33 to the surface of therotatable table 30. The outer surface of the die 33 is recessed toproperly receive the curved surface portion of the straight stock whichis to be bent into the annular shape; this die cross-section is clearlyillustrated in FIGURES 5 and 6, and FIGURES 8 through 11.

At the right-hand side of FIGURE 1 is shown a tool holder 34 which hasrigidly mounted thereto a guide wheel 35 and a forming block 36, Thecentral working portions of the guide Wheel 35, the forming block 36,and the die 33 all lie in a common horizontal plane. The guide wheel 35is mounted on a shaft 37 which is fixed to a bracket 38 for rigidsecurement to the tool holder 34. The guide wheel 35 is rotatable freelyabout the shaft 37 and is shaped to a cross-section to suit the stock tobe rolled. For example, FIGURE 5 illus trates a guide wheel of propercross-section for use with open channel U-shaped stock, whereas FIGURE 6illustrates a guide wheel 35 of proper cross-section for guiding stockof tear-drop or closed U cross-section. The forming block 36 is attachedto the tool holder 34 so that it faces the rolling die 33 atapproximately the point of contact of the latter with the stock to berolled. The function of the forming block 36 is to guide the stockaccurately into the recess in the rolling die 33 and also, if openchannel stock is being used to form the latter to a tear-dropcross-section just prior to bending. The forming block 36 may be seen invarious views in FIGURES 5 through 9, to which later reference will bemade.

The tool holder 34 is designed to permit adjustment in both thehorizontal and vertical directions so that the guide wheel 35 andforming block 36 may be accurately located with respect to the recess inthe rolling die 33, and also to allow the guide wheel 35 and formingblock 36 to be retracted for easy installation and removal of thematerial to be rolled.

The stock 39 for forming into the rolled annular ring is initially inthe form of a straight length of U-shaped or tear-drop shaped channelwhich has been previously roll formed carbon steel strip or sheet. Withthe tool holder 34 and attached guide wheel 35 and forming block 36retracted, the stock 39 is entered into the recess on the die 33 and aclamp 40 is loosely mounted to secure the stock 39 to the rolling die33. The tool holder 34 is now moved into position with the channel legsinserted into the guide block 36 and the guide wheel 35 in engagementwith the stock, as illustrated in FIGURE 1.

'set-up operation. This tear-drop forming of the leading 'edge of thestock 39 is necessary so that the guide block 36 may be moved into itsworking position and so that the clamp 40 may be secured. This will bemost clearly 'seen from a reference to FIGURES 7 and 10 whichrespectively illustrate the forming block 36 and clamp 40'. Referringfirst to FIGURE 7, it is seen that the right-hand edge 45, which isproximate the guide wheel 35, is apertured to a width sufficient toaccommodate the open U channel stock, but that the left-hand edge 46 isapertured to a much smaller width sufiicient only to accommodate atear-drop cross-section piece of stock. Since this is so, a portion ofthe stock 39 must be tear-dropped for a suflicient distance from itsleading end so that it may be accommodated within the narrow aperturedend 46 of the forming block 36. Referring now to FIGURE 10, it is seenthat the clamp 40 includes a generally U-shaped yoke portion 44surrounding the rolling die 33 and extending therebeyond, aV-shaped-recessed block 42, a pin 43, for locking the block 42 to theyoke 44, and a bolt 41 threaded through the yoke 44 and bearing againstthe inside of the rolling die 33 for pulling the block 42 toward therolling die 33 and thereby clamping the stock 39. The V-shaped recess inthe block 42 is required so that the stock 39 of tear-drop cross-sectionat its leading end may be securely clamped.

FIGURE 5 illustrates the form of the guide wheel 35 which is employedwith the open or U-shaped cross-sectional stock. It is seen therein thatthe guide wheel 35 is of a rounded edge disc shape so that it nestsclosely within the U-shaped stock. If, on the other hand, closed U orovoid shaped stock is used, there is no necessity for teardropping theshort section at the leading end of the stock since the ovoidcross-section is readily accommodated by the narrow apertured end 46 ofthe forming block 36, and the block 42 of clamp 40. The onlymodification to the apparatus required with this. stock shape. is thesubstitution of the guide wheel 35' illustrated in FIGURE 6 for theguide wheel 35 illustrated in FIGURE 5.

With the tool holder 34 set into its working position the stock 39 istangent to the die 33, nesting within the recess therein. The c1amp40 isnow drawn up tightly by means of the bolt 41 which thereby rigidly fixedthe leading end of the stock 39 to the die 33. The table 30 is nowrotated slowly in a counterclockwise direction and the stock 39 is ringformed about its longitudinal sectional axis by the bending momentsset-up between the clamp 40, the rolling die 33, and the guide wheel 35.The clamp 40 and guide wheel 35 of course must be of sufiicient strengthto resist these bending moments. During the rotation of the table 30,the forming block 36 guides the stock 39 and prevents cocking ortwisting of the latter during forming. In the event that open orU-shaped stock is being formed, the tapering sides of the forming block36 close the open stock to the desired ovoid shape by a pressing actionon the opposed open legs of the U-shaped stock. This forming action isclearly illustrated in the showing of FIGURE 8.

Referring now to FIGURE 2, it will be seen that after the table 30 hasrotated through about 270 degrees, the clamp 40 and the leading end ofthe stock 39 tend to interfere with a continuation of the formingoperation by approaching butting relation with the remaining straightstock which has not yet passed beyond the guide wheel 35. A second clamp47, identical to the clamp 40 is now attached to the stock 39 androlling die 33 as indicated in FIGURE 2. The first clamp 40 is nowremoved with the consequent freeing of the leading end of the stock 39.With approximately degrees of the formed ring free of the die 33, theleading edge may be readily displaced and lapped over the remainingportion of the straight stock 39, rotation of the table 30 then beingresumed until the full circle has been formed.

The length of the stock 39 must be such that a full circle may be rolledbefore the trailing end of the straight stock passes beyond the guidewheel 35, this being illustrated in FIGURE 3. The tool holder 34 is nowretracted thus disengaging the guide wheel 35 and forming block 36 fromthe rolled annulus, the clamp 47 is removed and the annulus disengagedfrom the rolling die 33. The resulting annulus includes sufficientoverlap of the end portions to permit a sizing and trimming operationand is illustrated in FIGURE 4.

The diameter of the annulus illustrated in FIGURE 4 is determined by thediameter of the rolling die 33 and what may be called spring-back or theincrease in diameter due to the elasticity of the metal stock. Therolling die, diameter and the spring-back characteristic areinterdependent, and in order to accurately control the finished size ofthe rolled annulus the relationship between diameter and spring-back forthe material being formed must be known. A large diameter annulusundergoes less deformation during the forming process than does anannulus of smaller size, and therefore has a more elastic spring-back.In the rolling of a small annulus, the spring-back may be very slight,and in some cases so small that the formed annulus cannot be removedfrom the die. In a case such as this, when the spring-back becomes lessthan twice the radius of the recess in the rolling die 33 the lattermust be made in two sections. These two sections are of a form whichwould be obtained by splitting the rolling die 33 in a horizontal planethrough the root of the recess therein. These sections are boltedtogether prior to the start of the forming operation and unboltedsubsequent thereto so that the upper section may be removed and theannulus released.

The rolled annulus of FIGURE 4 is now ready to have its overlappingstraight ends trimmed OE and to have its inside diameter accuratelysized. A metal cutting bandsaw may be used for the cutting operation inconjunction with a special jig upon which the annulus of FIGURE 4 ismounted. Such a jig is shown in FIGURE 12, as is also a metal cuttingband-saw having a table 50 and a saw blade 51. The jig consists of abase plate 52 upon which is mounted a ring 53 having an accuratelymachined outside circumference conforming to the desired finished insidediameter of the annulus. A slot 62 is cut into the base plate 52 and isaligned with the slot in the band-saw table 50 to permit free passage ofthe saw blade 51 inwardly for cutting the rolled annulus 39.

The untrirnmed annulus is placed on the base plate 52 around the sizingring 53 with the overlapping end sections centered on the slot 62. Inorder to secure the rolled annulus firmly in position and to insureclose conformity to the outer machined surface of the sizing ring 53, aset of eccentric cams 54 through 60 are employed, these cams beingrotatably secured to the base plate 52 by bolts 63. The cams 54 through60 are so arranged that the direction of the friction forces exerted onthe annulus by each cam is always toward the free end of the ring,thereby forcing any excess material into the straight scrap sections. Itwill be observed that the cams 54 through 57 are all tightened in aclockwise rotational direction whereas the cams 58, 59 and 60 aretightened in a counterclockwise rotational direction. A proper camtightening sequence in order to insure close conformity of the annulusto the sizing ring 53 would be as follows: first, tighten the cam 57 andthen tighten the remaining cams in pairs beginning with the pair 56 and58, followed by the pair 55 and 59, and finally the pair 54 and 60. Oncethe cams have been tightened a check may be made with a feeler gage forexcessive clearance between the sizing ring 53 and the annulus 59, andif sufiiciently close conformity between the two exists a clean straightsaw cut through the overlapped ends is made by moving the saw blade 51inwardly through the slot 62 and into cutting engagement with theoverlapped ends. When the cut has been completed, the sized and trimmedannulus 39 is removed from the sizing and cutting jig by releasing thecams 54 through 60. The sized and trimmed annulus is now in the form ofa hollow toroid and is ready for the welding of a band to the outsidediameter to form the finished T-shaped selfequalizing ring.

After removing the sized and trimmed annulus from the trimming jig, itis placed in a welding jig such as that shown in FIGURES through 18.Referring first to FIGURE 15, there is seen a fixture 80 having avertically extending back-stopping section 87 of circular configura tionwhich conforms to the desired inner diameter of the hollow toroid 39.The relationship of the toroid 39 to the fixture 80 and the variousother component parts of the welding jig will be best understood byreference to FIGURES l7 and 18, although the method of set-up forwelding will be described in connection with FIGURES l5 and 16.

The toroid 39 having been placed upon the fixture 80 with its insidediameter surrounding the vertically extending portion 87, the ellipticalcams 70 through 79 are employed to set-up the toroid 39 for the Weldingoperation. All of the cams 70 through 79 excepting the cams 70 and 75may be brought into engagement with the toroid 39 by clockwise rotation.The two cams 70 and 75 are brought into engagement by counterclockwiserotation. The cam 70 is utilized with the remaining cams excepting 75 toinitially clamp the toroid 39 to the welding fixture, whereas the cam 75is used with the remaining cams excepting cam 70 to clamp the outer band85 around the toroid 39 for welding thereto.

The first operation, which involves the clamping of the toroid to thefixture 80 is performed as follows. With the toroid 39 in position aspreviously described, the cam 70 is rotated counterclockwise intoclamping engagement, thus tending to push the toroid 39 in a clockwisedirection. The cams 71 through 79, excepting cam 75, are thensuccessively tightened by clockwise rotation. This successive tighteningoperation forces the free end of the toroid 39 in a counterclockwisedirection, thereby causing it to conform closely to the back-stoppingportion 87 of the fixture 80. The ends of the toroid 39 are thus broughtinto butting engagement.

With the toroid 39 so cammed, a plurality of segment clamps 88 aresecured to the fixture in clamping engagement with the toroid. As bestseen in FIGURE 18, the segment clamps 88 comprise a formed metal portion84 and a bolt and nut 86. The formed metal portion 84 is so shaped inrelationship to fixture 80 and the toroid 39 as to securely clamp thelatter into the desired position as shown. The formed metal portion 84is securely fastened to the vertical backing portion 87 of the fixture80 by the bolt 85 and nut 86. With the toroid 39 securely clamped to thefixture 80 by the segment clamps 88, the engaged ones of the eccentriccams 70 through 79 may be released so that the band 85 may be placed inwelding position against the outer circumference of the toroid. Therelative positions of the band 85 and the toroid 39 are best seen in thecross-sectional view of FIGURE 18.

It will be observed from FIGURE 16 that whereas the ends of the toroid39 are buttingly engaged between the eccentric cams 70 and 79, thebutting ends of the band 85 are positioned between the eccentric cams 74and 75. With the band 85 positioned as shown in FIGURE 16, the eccentriccams are again employed to bring the band 85 into close conformance withthe outer circumference of the toroid. This is accomplished by firsttightening the formerly unused eccentric cam 75 by counterclockwiserotation. The remaining cams are then tightened by clockwise rotation,tightening in order the cams 76 through 79 and then the cams 71 through74. It should be noted that the cam 70 remains disengaged during thisoperation. The band 85 is properly vertically positioned by means of theclamping plates 81 affixed to the top of the eccentric cams 70 through79 by tightening the nut 83 downwardly on the bolt 82 which secures eachof the cams to the fixture 80. As before, these details are best seen inthe views of FIGURES 17 and 18.

With the hollow toroid 39 and the band 85 properly positioned andsecurely clamped, long tack welds are made between the segment clamps 88to secure the band 85 to the toroid 39. The toroid 39 and band 85 maynow be released from the welding jig, turned over, and tack welded onthe opposite side. The toroid 39 is now finish welded to the outer band85 with intermittent welds and this may be done either in the weldingjig or after removal from the jig depending upon the heat dissipatingability of the welding jig. It is essential that both sides of theassembly comprising the toroid 39 and the band 85 be tack welded beforeeither side is finish welded or the shrinkage produced by the finishweld will tend to open up the closed edges of the tear-drop section 39and change its shape. FIGURE 19 illustrates a completed assembly of atoroid 39 and band 85 after removal from the welding jig.

The assembly illustrated in FIGURE 19 may be used either as anequalizing ring or as an end bell in a flange or welding endconstruction for an expansion joint. If the assembly is to be used as anend bell, the butt joint in the toroid 39 is reinforced by a weldedgusset plate on the side which is not in contact with the corrugatedbellows element of the expansion joint. If, however, the assembly ofFIGURE 19 is to be used as an equalizing ring, it must be first stressrelieved and then cut in half to form a pair of symmetricalsemi-circular sections. These semi-circular half sections are made bycutting through the outer band 85 in line with the unwelded butt jointin the toroid 39, and by making a second cut 180 degrees away throughthe butted ends of the outer band and through the toroid. These alignedtwo cuts through the outer band 85 and the toroid 39 are illustrated inFIGURE 20 as the cuts 100 and 101.

The half-sections may be applied to the corrugated bellows element of anexpansion joint to form a complete equalizing ring by means of weldedbutt straps. A pair of these butt straps 90-90 is illustrated in FIGURE20. FIGURE 21, which is a sectional view taken along the lines 2121 ofFIGURE 20, shows the butt strap 90 fillet welded to the outer band 85 asby the Welds 9191. FIGURE 23 shows in fragmentary sectional view such anequalizing ring in place about the corrugated bellows element 92 of anexpansion joint. The butt strap 90 must be of sufiicient cross-sectionto develop the same strength as the outer band 85, and the length of thefillet welds 91 must be such that the shear strength is equivalent alsoto the strength of the band 85.

An alternative to the use of welded butt straps 90, and one which allowsfor demounting of an equalizing ring after it has been installed on thecorrugated bellows element of an expansion joint, is illustrated inFIGURE 22. This method provides for the Welding of a pair of boltinglugs 89-89 to the assembly of FIGURE 19, in the configurationillustrated in FIGURE 22. Each of the bolting lugs 89 contains apredrilled bolting hole 93. After the bolting lugs 89 have been Weldedto the outer band 85, the entire assembly is stress relieved and cut inhalf along the dashed lines 9494, thus completing the equalizing ring.

It will be understood, of course, that the present invention ashereinbefore described and as shown in the accompanyings is susceptibleof various changes and modifications which may be made from time to timewithout departing from the general principles or spirit of theinvention, and accordingly it is intended to claim the same broadly asWell as specifically, as indicated by the appended claims.

What is claimed as new and useful is:

1. In apparatus for making a stress equalizing ring element for use withthe corrugated bellows element of an expansion joint, the combinationincluding bending apparatus comprising a rotatable circular form aboutwhose periphery a piece of longitudinally straight stock is to be bentinto a substantially spiral shape, first guiding and bearing means forsupportably engaging the straight stock at a point substantiallyopposite the point of engagement of said stock with the periphery ofsaid circular form, said first guiding and bearing means comprising arecessed pinch block having apertured leading and trailing faces, therecess being formed by a pair of sloping planar sidewalls runningbetween the face apertures with the leading face aperture being of thesame depth as that of the trail: ing face aperture but of greater width,second guiding and bearing means for engaging the stock on the same sideas and at a point in advance of its engagement with said first guidingand bearing means, and third bearing means comprising a clamp forclamping the lead-end of the stock to the periphery of the rotatablecircular form and causing it to spirally enclose the periphery of saidcircular form as the latter is rotated by setting-up bending moments insaid stock, the bending moments being set-up by counter-rotationalforces about a fulcrum established at the point of engagement of thestock with the periphery of the rotatable circular form, one of saidcounter-rotational forces being established by said second guiding andbearing means and another of said counter-rotational forces beingestablished by said third bearing means, said first guiding and bearingmeans preventing the stock from twisting and bowing and therebypreventing any appreciable shift of the fulcrum along the periphery ofsaid rotatable circular form.

2. The combination according to claim 1 wherein said second guiding andbearing means comprises a rotatable circular disc adapted to fit closelywithin the open channel of stock of U-shaped cross-section.

3. The combination according to claim 1 wherein said second guiding andbearing means comprises a rotatable Wheel containing an open V-shapedcircumferentially extending recess adapted to include therein thesidewalls of stock of tear-drop cross-section.

References Cited in the file of this patent UNITED STATES PATENTS1,575,014 Suell Mar. 2, 1926 1,849,181 Francis Mar. 15, 1932 2,244,029Strayer et al. June 3, 1941 2,685,928 Bergh Aug. 10, 1954 2,812,004 HuetNov. 5, 1957 2,882,953 Huet Apr. 21, 1959 2,974,706 De Witt Mar. 14,1961 2,996,100 Newhall et al Aug. 15, 1961

1. IN APPARATUS FOR MAKING A STRESS EQUALIZING RING ELEMENT FOR USE WITHTHE CORRUGATED BELLOWS ELEMENT OF AN EXPANSION JOINT, THE COMBINATIONINCLUDING BENDING APPARATUS COMPRISING A ROTATABLE CIRCULAR FORM ABOUTWHOSE PERIPHERY A PIECE OF LONGITUDINALLY STRAIGHT STOCK IS TO BE BENTINTO A SUBSTANTIALLY SPIRAL SHAPE, FIRST GUIDING AND BEARING MEANS FORSUPPORTABLY ENGAGING THE STRAIGHT STOCK AT A POINT SUBSTANTIALLYOPPOSITE THE POINT OF ENGAGEMENT OF SAID STOCK WITH THE PERIPHERY OFSAID CIRCULAR FORM, SAID FIRST GUIDING AND BEARING MEANS COMPRISING ARECESSED PINCH BLOCK HAVING APERTURED LEADING AND TRAILING FACES, THERECESS BEING FORMED BY A PAIR OF SLOPING PLANAR SIDEWALLS RUNNINGBETWEEN THE FACE APERTURES WITH THE LEADING FACE APERTURE BEING OF THESAME DEPTH AS THAT OF THE TRAILING FACE APERTURE BUT OF GREATER WIDTH,SECOND GUIDING AND BEARING MEANS FOR ENGAGING THE STOCK ON THE SAME SIDEAS AND AT A POINT IN ADVANCE OF ITS ENGAGEMENT WITH SAID FIRST GUIDINGAND BEARING MEANS, AND THIRD BEARING MEANS